Solar water heater



1936. H. M. CARRUTHERS 2,065,653

7 SOLAR WATER HEATER Filed April 28, 1934 W W WWW Patented Dec. '29, 1936 U NITED STATES PATENT OFFICE some. WATER. HEATER Henry M. Carruthers, Miami, Fla. Application April as, 1934, Serial No. 722,986

4 Claims. (01. 126-271) This invention is a coil structure particularly designed for use with solar heaters.

It is well known with respect .to the operation of solar heaters, that it is necessary to have each line of coil so arranged that the water to be heated will travel upwardly. The customary practice is to run the water through a coil ex-' tending the entire length of theheating cabinet. This is objectionable, however, because it is necessary to maintain the spacing of the convolutions at a substantial distance, in order to get the proper pitch of the coil convolutions, so as to insure free circulation. One of the objects of the present invention is to overcome this objection by providing a coil structure in which the convolutions may be brought closer together, and thereby provide a compact structure with increased heating surface. -A further object is to provide a coil structure in'which a plurality of to coil sections lead from a common cold water inlet in such manner that the coil convolutions may be placed closer together than heretofore, and still have sufiicient pitch to allow the proper flow of water. 1 The invention will be hereinafter fully set forth and particularly pointed out in the claims In the accompanying drawing:

Figure 1 is a side elevation of a coil structure two outlet branches. The inlet end of the de- 5 40 livery pipe II is connected with a similar coupling I4, 1. e. an outlet branch and two inlet branches. Leading from one inlet branch of the coupling I3 is the inlet portion a of a heating tube I5, said tube being bent into a plurality of 45 zig-zag convolutions to form the heater unit A,

the outlet portion a of said tube being connected with one of the branches of the coupling I4. It will be observed that the convolutions of the tube I5 lie between the pipes III and II.

50 Connected with the other outlet branch of the coupling I 3 is the inlet portion b of a heating tube I6, said tube-being bent into a plurality of zig-zag convolutions to form the heater unit B, the outlet portion b' of said tube being connected 55 with one of the inlet branches of the coupling I4,

or one of the units may be wider than the other, 5

and arranged as shown in Figure 2, omitting the unit C.

It will be noted that in the form illustrated in Figure l, the tubes I5 and I 6, the pipes I0 and I I, and the connections l3 and all lie in the 10 same common plane, and that both pipes I0 and I I are inclined so that they are respectively in axial alignment with the inlet portion' b and the outlet portion 1) of the tube I6. In practice, the tubes I5 and I6 are secured in suitable l6 manner, such as by soldering to a metal backing D preferably in the form of sheet copper, so that the coils and the inlet and outlet pipes all lie in approximately the same plane.

In operation, the effect of the heat of the sun upon the sheet metal backing and the tubes connected thereto is such that water supplied by the pipe I0 is caused to circulate through the coils and to flow upwardly through the respective tubes I5 and I6, and out of the pipe II, in a manner which is well understood in the art relating to solar heaters.

Referring to Figure 2, the heater units A and B and their connections with the supply and discharge pipes are substantially the same as in Figure 1, except that the unit B is much wider than the unit A, as above indicated. As shown in said Figure 2, II) designates the cold water inlet pipe and -I I the warm water outlet pipe. These pipes are respectivelyprovided with the multiple couplings I3 and M The zig-gaz or sinuous tube I 5 is connected at one end with one of the outlet branches of the coupling I3 and at its other end with one of the inlet branches I 4. It will also be observed that the convolutions of tube I6 are,

connected at one end to an outlet branch of the inlet coupling I3 and at the other end to one of the branches-of the coupling I4. As thus far described the construction is approximately the same as that shown in Figure 1. The form of the invention illustrated in Figure 2 differs from that illustrated in Figure 1, primarily in the provision of a third unit C consisting of a tube I I the con: volutions of which are connected by multiple branch couplings I1 and I8 respectively, with lower and upper convolutions of the coil I6. It is preferred to so arrange the convolutions of the coils A and C that theadjacently located small bends of the two coils are in staggered relation, and that the coil B is made of a width approxiand C, with the convolutions of the coil B fitting inside of the convolutions of the coils A and C, The operation-is the same as described in connection with Figure 1. V

The advantages of the invention will be readily understood by those skilled in the art to which the invention belongs. It will be particularlyobserved that by arranging a plurality of coils side by side in lieu of using one long coil, the convolutions may be brought closer together, thereby increasing the coil surface exposed to the thermal action of the sun, and without any reduction in the capacity of the heater. A further advantage is that the coils areso connected with each other that there is a substantially equal dist'ributlon oi the circulating medium.

Having thus explained the nature of the invention and described an operative manner, of

constructing and using the same, although without attempting to set forth all of the forms in which it may be made, or all of the forms of its,

use, what is claimed is:

1. A heat exchanger for solar heaters comprising two water heating tubes, each tube embodying a plurality of continuous, unbroken zig-zag convolutions all lying in the same common plane, and each provided with an inlet end and an outlet end, portions of the convolutions oi. one cell being extended into positions which overlap and lie between convolutions of the other coil, a common connection between said inlet ends, a common connection between the outlet ends, said outlet ends being higher than the inlet ends, a supply pipe connected with both coils at the common connection between said coils, said supply pipe being arranged in alignment with the first convolution of one of said coils, and a discharge pipe connected with said coils at the common connection between them, said discharge pipe being arranged in alignment with the-last convolution of one oi. said coils.

2. A heatexchanger for solar heaters comprising water heating tubes arranged laterally with respect to each other, each or said tubes embody-' ing a plurality of continuous unbroken zig-zag convolutions all lying in the same plane and provided with an inlet end and an outlet end, the convolutions of one of said tubes being of greater length than those of the other tube, portions of mately equal to the combined widths oi! coils A tween the outlet ends of said tubes, said outlet ends being higher than the inlet ends, a supply I embodying a plurality of convolutions of zig-zag form, the convolutions of the third tube being of approximately the same length as the combined lengths of 'the other tubes and in alternating nested relation with respect to the latter, the inlet and outlet ends of the first mentioned tubes being respectively connected with convolutions of the longer tube, a supply pipe connected with the lower end of the longer tube, and adis charge pipe also connected with the longer tube, said'tubes and. said pipes all lying in the same common plane.

4. A solar heater comprising a flat-metal back ing and two laterally spaced water heating tubes spread laterally with respect to each other and so supported as to lie in physical contact with the surface of said backing, each tube embodying a plurality of continuous, unbroken convolutions of zig-zag form, a third water heating tube also embodying a plurality of continuous,

unbroken convolutions of zig-zag form but longer than the convolutions of either 01 the other tubes, the convolutions oi! the said third tube being nested between and alternating with convolutions of both oi! the first mentioned laterally spaced tubes, so that the longer tube occupies a space which is approximately within the area occupiedby the two shorter tubes, each tube having an inlet portion and an outlet portion, the outlet portions being higher than the inlet portions, a cold water supply pipe, a, common connection between said supply pipe and the longer tube and one of the first mentioned tubes, a hot water discharge pipe, a common connection between said longer tube and the same one of the two first mentioned tubes, and supply and discharge connections between the other one of the two first mentioned tubes and the longer tube, said pipes and said tubes all lying in the same common plane HENRY M. CARRUTHERS, 

